Analysis and design of soil nail walls in high plasicity clays

The main objective of this research is to evaluate the method used by TxDOT in designing soil nailed walls in expansive soils and to make recommendations to improve design procedures. The end result of this research is to provide design guidelines for soil nailed walls in high plasticity soils considering the additional lateral pressures generated by soil expansion.

The present TxDOT design procedure for common retaining structures in cuts, such as soil nailing, tied-back, and drilled shaft walls, is based on lateral pressures calculated from classical Rankine's or Coulomb's methods. This considers the drained shear strength parameters and does not include any lateral pressure due to moisture changes in the expansive soils. The additional lateral pressure due to changes in moisture content in expansive soils could be 10 to 20 times higher than those estimated by classical theories. This research is divided into two parts: (i) Analysis of soil nail walls in expansive soil using the GeoStudio software. (ii) Design recommendations for soil nailed wall system in expansive clay. The focus of this research study is: (1) Horizontal pressure pattern in expansive soils on soil nail retaining structures. (2) Tensile force distribution in soil nails due to expansive soil.